紫外线激活钙调磷酸酶PP2B介导AFF4转录复合物调控SOX2促进黑色素瘤干性表型的机制研究

紫外线是黑色素瘤最突出的致病因素，云南地处高原，黑色素瘤高发。黑色素瘤起始细胞MIC是恶性进程的关键。然而其机制仍未阐明。我们采用mRNA芯片获得黑色素瘤的特异癌基因AFF4，证实AFF4的表达与临床分期和肿瘤厚度正相关；敲减AFF4后，SOX2表达减低，MIC自我更新能力下降；深入研究提示AFF4与CDK9存在互作关系；提示AFF4转录复合物可能调控SOX2参与MIC干性调节。进一步研究发现：抑制钙调蛋白CaM，阻断靶酶PP2B，Ca2+信号通路阻断，AFF4、CDK9和SOX2的表达降低，MIC自我更新能力下降。由此，我们从干性基因转录调控视角，以Ca2+信号通路为切入点，阐明紫外照射激活细胞内Ca2+信号通路，干预AFF4转录复合体调控SOX2转录，参与调节MIC干性表型的机制，为黑色素瘤治疗提供新的候选靶点。

The incidence of melanoma are significantly high in Yunnan due to strong ultraviolet radiation. Melanoma-initiation cells(MIC) is a key factor of the recurrence, metastasis and resistance to radiotherapy and chemotherapy. However, its mechanisms remain unclear.. To our interst, we obtained melanoma specific oncogene AFF4 by mRNA chips and AFF4 was highly expressed in melanoma and closely related to clinical stage and tumor thickness as showed by immunohistochemistry. Moreover, the expression of SOX2 was decreased and the ability of self-renewal was inhibited, after knching down AFF4. the inteaction between AFF4 and CDK9 was observed by mmunoprecipitation. These results suggest that AFF4/P-TENb complex plays an important role in MIC reprogramming. Furthermore, bioinformatics analysis suggested that AFF4-related complex targeted SOX2 was involved in MIC reprogramming. Importantly, further study found that inhibition of Ca2+ signal pathway can block the function of AFF4/CDK9 complex.. Based on these results, we hypothesize that AFF4 transcription complex regulates self-renewal of human melanoma-initiationg cells by targeting Ca2+ signal pathway . In this study, we intend to further expore the possible mechanism that AFF4 transcription complex regulates the stem-like function of melanoma-initiating cells by UVB avtiation Ca2+ signaling pathway,which wound provide a new target for the treatment of melanom.